Incinerator stoker grate construction



J. F. TURNER, SR, ETAL INCINERATOR STOKER GRATE CONSTRUCTION Aug. 16, 1966 8 Sheets-Sheet 1 Filed Nov. 12, 1963 INVENTORS James F; Torr/vet 57",

C(f/l/fczm H, B Q77,

77cm? cmcZ C/crrenae H. ml'vh, c/r',

BY/ WM ATTORNE Aug. 16, 1966 J. F. TURNER, sR.. ETAL 3,266,447

INCINERATOR STOKER GRATE CONSTRUCTION 8 Sheets-Sheet 2 Filed Nov. 12, 1963 INVENTORS (/ames F, Turner, S71,

and Clarence H.15m1'+h,d'r:

. ATTORN Aug. 16, 1966 J. F. TURNER, sR., ETAL 3,266,447

INCINERATOR STOKER GRATE CONSTRUCTION 8 SheetsSheet 3 Filed Nov. 12, 1963 INVENTORS Games FT Tuv'ne wf/h'czm 1 7 5C177L777 car; are? Clarence H,5'mr/+h, c/Y,

V I ATTORNEY Aug. 16, 1966 J. F. TURNER, sR., ETAL 3,266,447

- INCINERATOR STOKER GRATE CONSTRUCTION Filed Nov. 12, 1963 s Sheets-Sheet 4 I as I g/czmes E Turner, S11,

w/H/am H, Barr/warn and C/an-cznce H,,3'-rn/'1h c/v'.

INVENTORS ATTORNEY Aug. 16, 1966 J. F TURNER, SR., ETAL 6,

INCINERATOR STOKER GRATE CONSTRUCTION Filed Nov. 12, 1963 8 Sheets-Sheet 5 26 INVENTORS dame-s E TMTHET, 5r, ZCh'l/fec "m H. B cc'r'f'mozn cmc? C/ar as H. Sm/fh, c/r.

ATTORN Aug. 16, 1966 J. F. TURNER, SR, ETAL 3,266,447

INCINERATOR STOKER GRATE CONSTRUCTION 8 Sheets-$heet 7 Filed Nov. 12, 1963 INVENTORS C/ames F7 TLLrrlz-Y, 57,,

wz'llz'am h, B cvr'fmezn and Clarence H, SmH'h, (/7:

' ATTORNE J. F. TURNER SR ETAL 3,266,4'47

Aug. 16 6 n Ids rs, H:

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ORN

United States PatentOf INCINERATOR STOKER GRATE CONSTRUCTION James F. Turner, Sr., William H. Bartman, and Clarence H. Smith, Jr., Baltimore, Md., assignors to Flynn &

Emrich Company, Baltimore, Md., a corporation of Maryland Filed Nov. 12, 1963, Ser. No. 322,883 8 Claims. (Cl. 110-8) This invention relates to an incinerator stoker in a continuously operating refuse burning furnace. In such a unit .mixed refuse, as collected from residential, commercial, and industrial sources, is fed into the furnace from a feed chute, or hopper, continuously by the action of the stoker. The stoker is made relatively long as compared to the width, in order that the refuse, in passing through the furnace, remain in the furnace long enough at temperatures sufiiciently high to reduce all combustib e matter and develop a sterile residue. This material, in passing through the furnace, is kept porous, clinker free, alive, and moving by the action of the stoker. The stoker imparts a cascading motion to the refuse. This allows a higher degree of destructor efiiciency than heretofore available from other stokers. I

The stoker grates using alternate motion, as set forth in the patent to Turner et al. 2,777,406 of January 15, 1957, lift the material on the grate surface, agitate it, and thrust it forward. This action fills in the voids which develop from rapidly burning refuse and breaks up the stubborn, compacted masses. Thus more uniform distribution is effected on the grates, promoting more uniform conditions for air distribution, combustion, and general furnace conditions.

The continuous operation of the alternate moving stoker bars assures that no attendant manual labor is required to destroy the refuse and to effect continuous resi- 'due disposal to sluices, water-filled conveyors, ,or other suitable means of removal. The continuous operation is obtained by mechanism illustrated in the patent to Turner et al. No. 3,057,309, of October 9, 1962. This mechanism will also operate any selected section sets of grates mechanically, or by. an overriding manual control, as may be desired.

During operation of the furnace, a relatively high temperature is carried to insure as complete destruction of combustibles as possible; It is, therefore, imperative that the alternately moving grate bars comprising the grate surface be operable until the combustible material is burned out and temperatures inthe furnace, as well as residue on the grates, are below the point where fusion of the residue into solid masses can take 'place. If such fusion into clinker takes place during operation, large quantities of combustible materials are sealed in the mass and discharged from the furnace, oftentimes it is necessary with considerable attendant manual labor to break up this clinker formation, to prevent obstructing or damaging the residue disposal system or equipment. If the stoker were shut down when the regular bed of burning refuse is on the grates and furnace temperatures at usual levels, the burning mass would rapidly lose its porosity, internal fire bed temperatures would increase, and fusion of the elements within the fire bed would follow. When cooled,

-to the rear, shield edge of the moving grate bar.

3,266,447 Patented August 16, 1966 ICC and moving continuously through the furnace to avoid costly and unwanted shut-down.

The mixed ref-use, as charged to the furnace, has in it a considerable quantity of irregular metal and glass shapes such as ball bearings, spark plugs, bolts, nuts, nails and the like which would, from time to time, lodge in a position between grate bars so as to impede the operation of the moving bars. This would sometimes occur when the grate bars were trying to rise by turning on their trunnions, and sometimes when the grate bars were coming down to their normal rest position. Also, simi ar noncombustible material and abrasive material enter open sockets causing excessive wear, and add to the impediments. It will be readily appreciated that the design and arrangement of the grate bars is critical. The design presented herein has been thoroughly tested and proved capable of continuous operation.

In the present disclosure, between each alternately moving grate bar is a stationary or spacer grate bar. The moving bars have a fixed replaceable trunnion at each end of a hard wear-resistant material. Each trunnion is secured by a bolt to the grate bar. The trunnion has a protruding section which fits into a mating depression in the grate bar. This prevents the trunnion from turning on thebolt, and at the same time, removes the support load imposed by the grate from the bolt, as well as the turning load, when moved by applying power to the grate lugs.

The trunnions are inserted in sockets at either end of the grate bars to support the grate bars on a suitable frame. These sockets are also of a hardened material to resist wear. The opening in the socket is round, completely surrounds the trunnion, and has a reasonably close tolerance to prevent the admission of larger noncombustible material, and as much as possible the abrasives that tend to filter into the sockets.

Thetop of the stationary grate is set in line with the top of the adjacent moving grate rear edge where that edge of the stationary bar is in proximity to and adjacent The shield is on an arc concentric with the turning axis of the grate bar. As the moving bar rises, by turning on its trunnion, the angle formed by the top of the stationary grate bar and the shield is greater than with the grate Surface. This allows the stationary grate bar to act as a scraper to the shield, and prevents solids from impeding the operation of the moving grate bar in either direction. By Way of explanation, it has been found that, when the angles are less than 90, there is a tendency to drag materials into the angle formed causing the material to wedge, and on occasion impede the operation of the moving grate bar. The edge of the stationary grate bar is placed at a minimum practical tolerance to the shield of the moving grate bar. This tolerance places a vertical tangent to the shield slightly below the upper surface of the moving grate bar. The top edges are in a straight line with each other; however, in operating, wear takes place in linkages and pins, allowing the shield edge to sag and drop below the stationary bar edge. When this occurs, adjustment is provided in the connecting linkage to bring the edge back in line with the stationary bar edge, thus taking out the effects of the wear. It is important to inspect the unit to ascertain that the moving bars do not drop below the stationary bar edge so far as to open up the bars to allow large articles to pass or wedge. When theshield edge drops below the stationary bar edge a close tolerance is retained, but a slight drop from the stationary grate to the moving grate, retains the free flow of materials from bar to bar as originally adjusted and maintains always a downward slope to all the bars. This allows several successive adjustments to replace the effects of wear before actual parts replacement is required. The parts referred to for replacement are principally the trunnions attached by bolts to and supporting the moving grate bar and the trunnion sockets. Both of these items are constructed of wear-resistant metals for long operational life.

The nose or forward edge of the moving grate bar is set adjacent to and above the edge of the stationary grate bar. Ideally, the elevation of this setting would have the stationary grate bar edge in line with the center line or axis of the nose edge, the edge being concentric with the axis. This then would give an angle of at least 90 between the two adjacent edges and allow the material to drop slightly in passing from one grate bar to the other. Since wear takes place on the trunnions and sockets from the beginning of operation, the moving grate bar forward edge is initially raised above the sta tionary grate bar edge an additional amount. The maxi mum limit of raising the center line or a line through the axis of turning of the edge above the stationary bar edge would be in a line vertical to the stationary bar edge and forming a tangent to the nose edge, normal to the grate surface. The elevation must be less than would create an impediment receiving opening between adjacent edges. Thus, as wear takes place and the moving bar sags, a line through the axis of the nose approaches the top of the stationary bar edge, maintaining a close tolerance and allowing material to flow freely from the moving grate :bar onto the stationary grate bar. When the wear approaches the point that the centerline of the nose edge Le, a line through the nose axis drops below the top of the stationary bar edge, the spacing tolerance will tend to increase and replacement of the worn parts, tr-unnions and sockets, is required to regain the original setting and avoid impediments interfering with operation. This parts replacement is infrequent and by inspection, can be predetermined in order to schedule such repair at a convenient time.

The objects of this invention are to provide a stoker that will operate continuously in the manner above described and that may be restored to the optimum operating condition in the minimum time of shut-down.

In the construction shown, tandem sets of bars are arranged with stationary roll grate bars on the lower end of each upper set and in each set each movable bar is elevated above its next lowest stationary bar at least the amount of the radius of the nose of the bar, to give the material the constant cascading action for its forward movement.

The above and other objects and advantages of the invention will be apparent from the following description and the accompanying drawings forming a part hereof and in which:

FIGURE 1 is a fragmentary side elevational view partly in section of the upper portion of one section set of bars with the operating mechanism for the movable bars.

FIGURE 2 is a continuation of the view of FIGURE 1 to the right.

FIGURE 3 is a fragmentary plan view partly broken away of the successive grate bars shown in FIGURE 1.

FIGURE 4 is an enlarged side elevational view partly broken away between two movable bar sockets showing the socket and bar retainer on the supporting channel.

FIGURE 5 is a fragmentary transverse sectional view on line 55 of FIGURE 4.

FIGURE 6 is a continuation to the right of the view of FIGURE 4.

FIGURE 7 is a fragmentary transverse sectional view on line 7-7 of FIGURE 6.

FIGURE 8 is a further continuation view to the right of FIGURE 6.

FIGURE 9 is a top plan view of the movable bar.

FIGURE 10 is a front elevational view of the same.

FIGURE 11 is an enlarged fragmentary front elevational view of a portion of the operating mechanism for the movable bar.

FIGURE 12 is a sectional view on line 1212 of FIGURE 11.

FIGURE 13 is a sectional view on line 1313 of FIGURE 11.

FIGURE 14 is a fragmentary sectional view partly broken away of two adjacent movable bars and their supports in the furnace.

FIGURE 15 is a sectional view on line 1515 of FIGURE 14. 7

FIGURE 16 is an end elevational view of a movable bar showing its connection in dotted lines with the connecting rod drive lug.

b FIGURE 17 is an end elevation of a stationary roll FIGURE 18 is a top plan view thereof partly broken away.

FIGURE 19 is an end elevational view of an intermediate stationary bar.

FIGURE 20 is a top plan view thereof partly broken away.

FIGURE 21 is a fragmentary front elevational view of the same.

FIGURE 2 2 is an enlarged fragmentary top plan view of a wide rear end stationary bar.

FIGURE 23 is an end view thereof.

FIGURE 24 is a front elevational view of an intermediate stationary bar partly broken away.

FIGURE 25 is an enlarged somewhat diagrammatic sectional view of a movable bar showing its proximity to its adjacent stationary bars.

In the drawings similar numerals refer to similar parts throughout the several views.

As similarly shown in the second above noted patent to Turner et al. 3,057,309, the present stoker is made up of a plurality of sets of stokers of identical construction mounted between furnace walls 1 on the channels 2 supported on the beam 3 assembly extending between the walls. Each section set has on the beams or channels 12 movable grate bars 4 with a stationary or fixed grate bar 5 on each side, above and below the movable bar. At the lower end of each section set, the stationary bar takes the form of a roll bar 6 having a depending edge extending to the next lower stationary bar of the adjacent section set and the first stationary bar beneath the roll bar edge is a wide stationary bar 7. The three forms of stationary bars all have projections 8 at their ends of inverted U formation and the top of the U is cut out as shown at 9 in FIGURES 17 through 24 and the legs 10 of the U shaped projections rest upon channel-s 12 supported by channels 2.

The movable bars 4 have endwise projecting trunnions 13 which are mounted in close fitting sockets 14 having symmetrically shaped projecting standards 15 resting on channels 12. Inverted U-shaped socket retainers 16 have end projections or legs 17 and 18 bearing upon the projecting standards 15 of adjacent sockets 14. The retainers likewise hold the projections 8 on the stationary bars with some clearance between them as shown in FIGURES 4 and 5. Bolts 19 pass through the upper ends of the retainers and through the upper edges 20 of the channels 12, passing through the openings 9 in the projections from the stationary bars where they are held on channels 12 by nuts 21. The lower end of the retainers are held by bolts 22 to the channels 12. Stops 23 and 24 are welded to the channels 12 to prevent slippage of the sockets and stationary or fixed bars respectively. The standards of the sockets and of the legs 10 of the projections on the stationary bars are slightly cut away as shown at 25 to allow space for the welding of the stops 2? and 24. This construction allows for the very ready replacement of the sockets after their wearing and it will be noted that the sockets are symmetrical in construction on both sides of their vertical centers so that they can be assembled at either side toward their respective grate. The roll bar 6 has a retainer of slightly different shape, as shown in FIGURE 6, with an elongated projection 18' resting on channels 12, held by stops 24. Likewise projection 17' on the retainer bar the wide stationary bar 7 is longer, as shown in FIGURE 6 to bear on channel 12.

The movable bars have opera-ting lugs 26 both at their ends and two spaced at their centers as shown in FIG- URE '9. These lugs have openings at 27 with a keyway at 28 .to receive pins 29 having welded at one end a key 30 fitting in the opening 27 and key-way 28. These pins receive thereon connecting bar drive lugs 31 and a sleeve 32 is on the other portion of the pins 29, the sleeve being held longitudinally spaced by cotter pins 33 and from rotating by the cut-outs 34 in the sleeves. Al-

ternate drive lugs are connected to a common connecting bar 35 and the alternate lugs 36 to bar 37 and each connecting bar is driven by a separate cylinder, bar 35 by cylinder 38 and bar 37 by cylinder 39, as mentioned in the second patent to Turner et al. above noted. The connecting bar drive lugs 36 of the other connecting bar 37 are on the opposite side of the alternate pins 29 from those shown in FIGURES 11 and 12 for spacing the drive lugs and bars, and this is accomplished simply by turning the pins end for end as shown in FIGURE 11 since the parts are interchangeable for both connecting bars. Although the movable grate Ibars could be operated at their .ends from the lugs shown thereon, they are preferably operated from their centers as illustrated in FIGURES to 13 inclusive.

The trunnions 13 and movable bars 4 have aligned openings 40 receiving screw members or bolts 41 therein to join the two together. These two parts likewise have mating tongues and grooves 42 and 42 extending radially of the bolts and positioned substantially horizontal to the upper surface of the grate bar to relieve the bolts from both vertical and torsional strain. The bolts are held in place by nuts 43 preferably tack welded to the grate bars as shown at 44. This construction allows forthe ready replacement of the trunnions upon their wear and their turning 180 if desirable should they wear unevenly.

As shown in FIGURE 25 and others the movable bars 4 have a shield 45 concentric with the trunnion which is itself concentric with the nose or forward edge of the movable bar and as shown in FIGURES 9 and 10 is in line with the forward edge on its outer surface. A Nertical tangent to the surface of the shield 45 strikes the shield slightly below the upper surface of the movable bar. The adjacent stationary bar, as shown in FIGURE 25, projects at its top forward edge to make as close a tolerance between the bars, movable and stationary, as is operatively satisfactory, and less than enough to prevent the receiving of any foreign pieces or incombustible matter that would impede the operation of the movable bar. It will be apparent from this FIGURE 25 that upon the elevation of the movable bar that the angle between the surface of the movable bar and the adjacent stationary bar is greater than 90 so that upon lowering the movable bar there is substantially no tendency to draw material down between the two bars to impede the lowering movement. That is, the stationary bar will serve as a scraper to the movable bar shield which is uniformly curved and concentric with its axis of rotation across its whole width. At both sides of the movable bar the stationary bars likewise extend to a pointed edge as SlJOIWI] and the movable bar axis should never fall below the projecting pointed edge of the stationary bar, so that the pointed edge of the stationary bar will serve as a scraper against the nose of the movable bar toremove material from it and prevent the drawing of impediments between thetwo bars to obstruct the movement of the movable bar.

In practice both the trunnions and their sockets wear and the tendency is for the movable bar to fall below its initial position and for this reason, initially the movable bar trunnion is positioned substantially above the stationary bar to allow for this wear. In the initial construction the axis is placed so that a vertical tangent to the movable bar nose is in substantially a vertical line with the adjacent edge of the stationary bar as shown in FIG- URE 25. This allows the wear of the trunnion and its socket to go from line 46 to line 47 and likewise wear occurs in the linkage for holding the swinging side of the movable bar up, so that wear lowers the rear edge of the movable bar from the initial position as shown in FIGURE 25 to the dotted line position as shown at line 48. Materials still flow down hill when this amount of wear takes place in its fall from the stationary bar to the movable bar, but the surface of the movable bar should not be allowed by wear to reach much below the position shown at line 48 before correction is made in the linkages by making the necessary compensating adjustment of the pull rods 49 and 50 through their respective adjusting nut and screw members 51 and 52 as shown in FIGURE 1, or by replacement of linkage parts for the purpose of restoring the upper position of the movable bar surface.

Close tolerances are provided between the trunnions and their sockets and the sockets are closed around their periphery to exclude substantially all objectionable foreign matter. Likewise the tolerances on both sides of the movable bar are brought as close as they will satisfactorily operate to exclude impediments to its operation.

As may be readily seen from FIGURES 1 and 2 of the drawings the movable and fixed or stationary bars are positioned in tiers and comprising pairs of bars. Each of the pairs of bars comprising a movable bar and a fixed bar. The fixed bar being positioned adjacent the rear edge of the movable bar and the grate surfaces of the said bars of each pair being on the same plane, the plane of each of the following pairs being progressively lower in the downward direction of the incline of the furnace grate bed and thereby positioning the respective pairs of bars in a tier formation.

The grate of this invention exceeded its required efiiciency considerably by continuous uninterrupted operation, largely it is believed, because of the relation of the grates to each other, the closed sockets, the close tolerance, the long wearing metals in the critical parts and the provisions for wear within the construction. Inspection and replacement and adjustment at suitable times prevent shutdowns during operating periods.

It will be apparent that various changes may be made in the details of the construction of the invention without departing from the spirit thereof or the scope of the appended claims.

What is claimed as new and is desired to be secured by Letters Patent is:

1. A furnace for burning refuse comprising a grate assembly having alternately fixed grate bars and movable grate bars which in normal position form a forwardly and downwardly inclined supporting surface for the refuse, downwardly inclined supporting means for said bars, a furnace frame on which said supporting means are mounted, said movable bars being pivoted at their upper forward edges so that they can be tilted forwardly at their rear edges to advance the refuse and then be retracted, said supporting means comprising longitudinal downwardly sloping channels, trunnion sockets thereon having outwardly projecting supporting standards resting on said channels, projections on the ends of the fixed bars resting on said channels, socket and fixed grate bar retainers fixedly held to the channels by bolts, said retainers positioned over said fixed bar projections and socket standards to hold the sockets and fixed bars assembled on the channels, the projections comprising legs, certain of said retainer bolts passing between the legs of the projections for purposes of maintaining the normal operative position of the fixed grates in conjunction with the retainers, the movable bars having trunnions extending horizontally furnace frame on which said supporting means are mounted, said movable bars being pivoted at their upper forward edges so that they can be tilted forwardly at their rear edges to advance the refuse and then retracted, said supporting means comprising longitudinal downwardly sloping channels, readily reversible trunnion sockets thereon having outwardly projecting symmetrical supporting standards resting on said channels, inverted U-shaped projections on the ends of the fixed bars resting on said channels and inverted U-shaped socket retainers bolted to the channels over said fixed bar inverted U-shaped projections and symmetrically shaped socket standards to hold the sockets and fixed bars assembled on the channels, the

said retainers comprising bolts, certain of said bolts passing through the base and between the legs of the U-shaped projections the movable bars having trunnions extending horizontally from their forward upper ends pivoting in said sockets, said trunnions being screw attached to the said movable bars with interengaging radially disposed key and slot portions bisecting the axis of the trunnions and rotative axis of the movable bars for purposes of readily and partially rotating the trunnions to present an unworn wearing surface of the trunnions to the sockets.

3. A furnace for burning refuse comprising a grate assembly having alternately fixed grate bars and movable grate bars which in normal position form a forwardly and downwardly inclined supporting surface for the refuse, downwardly inclined supporting means for said bars, a furnace frame on which said supporting means are mounted, said movable bars being pivoted at their upper forward edges so that they can be tilted forwardly at their rear edges to advance the refuse and then be retracted, said supporting means comprising longitudinal downwardly sloping channels, trunnion sockets thereon having outwardly projecting supporting standards resting on said channels, projections on the ends of the fixed bars resting on said channels and socket retainers bolted to the channels over said fixed bar projections and socket standards to hold the sockets and fixed bars assembled on the channels, the movable bars having removable trunnions extending horizontally from their forward upper ends pivot ing in said sockets, horizontally extending screws between the trunnions and bars to hold them assembled together and radially interfitted parts integral with the trunnion and bars to relieve the screws from torsional strain.

4. A furnace for burning refuse comprising a grate assembly having alternately fixed grate bars and movable 'grate bars which in normal position form a forwardly and downwardly inclined supporting surface for the refuse, downwardly inclined supporting means for said bars, a furnace frame on which said supporting means are mounted, said movable bars being pivoted at their upper forward edges so that they can be tilted forwardly at their rear edges to advance the refuse and then be retracted and means including reciprocating bars connecting sets of movable bars together to be so moved together, the pivoted forward edge of each movable bar presenting an arched nose, concentric with its axis of movement, and spaced above the edge of the adjacent fixed bar a distance which is substantially at least the radius of the arc of the movable bar nose, whereby the rear edge of the adjacent fixed bar scrapes material from the arc of the nose of the adjacent movable bar upon its tilting.

porting means are mounted, said movable bars being pivoted at their upper forward edges so that they can be tilted forwardly at their rear edges to advance the refuse and then be retracted and means including reciprocating rods connecting sets of movable bars together to be so moved together, the pivoted forward edge of each movable bar presenting an arched nose, concentric with its axis of movement, positioned substantially above the edge of the adjacent fixed bar a distance which is substantially at least the radius of the arc of the arched nose of the movable bar, the rear edge of each movable bar being substantially aligned with the forward edge of the adjacent fixed bar, an arcuate shield projecting downwardly from the rear edge of each movable bar, the arc of the shield being concentric with the axis of movement of the bar, whereby the forward edge of the fixed bar scrapes material from the shield upon its retraction after tilting the bar upwardly, rotatable trunnions having means for fixedly positioning the trunnions at a predetermined rotative position on opposite ends of the movable bars comprising screw and interlocking elements, trunnion bearing sockets having standards for supporting each said movable bars, the fixed bars having inverted U-shaped projections at their opposite ends, said sockets and projections supported on the inclined channels, means for fixedly positioning the sockets and projections to the channels comprising retainer members therefor bolted to the channels together with stop members fixedly attached to the channels against which the forward edges of the projections and the forward standards of the sockets have abutment to prevent downward slippage on the downwardly inclined supporting channels.

6. A furnace for burning refuse comprising a grate assembly having alternately fixed grate bars and movable grate bars which in normal position form a forwardly and downwardly inclined supporting surface for the ref use, downwardly inclined supporting means for said bars, a furnace frame on which said supporting means are mounted, said movable bars being pivoted at their upper forward edges so that they can be tilted forwardly at their rear edges to advance the refuse and then beretracted and means including reciprocating bars connecting sets of movable bars together to be so moved together, the pivoted forward edge of each movable bar presenting an arched nose, concentric with its axis of movement, and spaced above the edge of the adjacent fixed bar a distance which is substantially at least the radius of the arc of the movable bar nose, horizontally extending trunnions on the ends of the movable bars and trunnion sockets closed over their tops on said downwardly inclined supporting means supporting said trunnions therein.

7. A furnace for burning refuse comprising a grate assembly having alternately fixed and movable grate bars which in normal position form a forwardly and downwardly inclined supporting surface for the refuse, down movable bars being pivoted at their upper forward edges so that they can be tilted forwardly at their rear edges to advance the refuse and then be retracted and means including reciprocating bars connecting sets of movable bars together to be so moved together, the pivoted forward edge of each movable bar presenting an arcched nose concentric With its axis of movement, the uppermost portion of the arched nose being positionedabove the rear edge of the adjacent fixed bar at a distance greater than the radius of the arc of the movable bar nose, the forward outer surface of the arched nose being substantially in a vertical line with the forward edge of the adjacent fixed grate bar, whereby the rear edge of the adjacent fixed bar scrapes material from the arc of the nose of the adjacent movable bar upon its tilting.

8. A furnace for burning refuse comprising a plurality of tandem sets of alternately actuated stoker bars which in normal position form a forwardly and downwardly inclined supporting surface for the refuse, downwardly inclined supporting means for said bars, a furnace frame on which said supporting means are mounted, said bars being movably mounted so that they can be tilted forwardly to advance the refuse and then be retracted, a 5

stationary grate bar positioned at the rear edge of each movable bar, the movable bars and their respective rearwardly adjacent stationary bars forming pairs of bars comprising a movable and stationary bar, the bars of each pair being on the same plane, the plane of each of the 10 following pairs being progressively lower in the down- Ward direction of the incline of the furnace grate bed as a whole, means including reciprocating rods connecting the tandem :sets of movable bars together to be so moved References Cited by the Examiner UNITED STATES PATENTS 1,278,405 9/1918 Watson 110-32 X 1,486,067 3/1924 Wymer 126181 2,777,406 1/1957 Turner et a1 110-8 3,057,309 10/1962 Turner et al 110-39 X FREDERICK L. MATTESON, 111., Primary Examiner.

together, the pivoted forward edge of each movable bar 15 M Y, ssistant Examiner. 

8. A FURNACE FOR BURNING REFUSE COMPRISING A PLURALITY OF TANDEM SETS OF ALTERNATELY ACTUATED STOKER BARS WHICH IN NORMAL POSITION FORM A FORWARDLY AND DOWNWARDLY INCLINED SUPPORTING SURFACE FOR THE REFUSE, DOWNWARDLY INCLINED SUPPORTING MEANS FOR SAID BARS, A FURNACE FRAME ON WHICH SAID SUPPORTING MEANS ARE MOUNTED, SAID BARS BEING MOVABLY MOUNTED SO THAT THEY CAN BE TILTED FORWARDLY TO ADVANCE THE REFUSE AND THEN BE RETRACTED, A STATIONARY GRATE BAR POSITIONED AT THE REAR EDGE OF EACH MOVABLE BAR, THE MOVABLE BARS AND THEIR RESPECTIVE REARWARDLY ADJACENT STATIONARY BARS FORMING PAIRS OF BARS COMPRISING A MOVABLE AND STATIONARY BAR, THE BARS OF EACH PAIR BEING ON THE SAME PLANE, THE PLANE OF EACH OF THE FOLLOWING PAIRS BEING PROGRESSIVELY LOWER IN THE DOWNWARD DIRECTION OF THE INCLINE OF THE FURNACE GRATE BED AS A WHOLE, MEANS INCLUDING RECIPROCATING RODS CONNECTING THE TANDEM SETS OF MOVABLE BARS TOGETHER TO BE SO MOVED TOGETHER, THE PIVOTED FORWARD EDGE OF EACH MOVABLE BAR PRESENTING AN ARCHED NOSE, CONCENTRIC WITH ITS AXIS OF MOVEMENT, SPACED SUBSTANTIALLY ABOVE THE EDGE OF THE ADJACENT STATIONARY BAR, TO GIVE THE MATERIAL A CONSTANT CASCADING FLOW IN ITS DOWNWARDLY FORWARD MOVEMENT. 